Blue azo dye and process of making same.



UNITED STATES PATENT OFFICE.

HUGO JAESSOHIN AND OSKAR KALTWASSEB, OF BERLIN, GERMANY, ASSIGNORS TOAOTIEN-GESELLSOHAFT FUR ANILIN FABRIKATION,

OF SAME PLACE.

BLUE AZO. DYE AND PROCESS OF MAKING SAME.

SPECIFICATION forming part of Letters latent No. 684,065, dated October8, 1901.

Application filed July 12, 1901. Serial No. 67 998. (No specimens.)

To all whom it may concern.-

, Be it known that we, Hueo J AESSOHIN and OSKAR KALTWASSER, of Berlin,in the Kingdom of Prussia, German Empire, have invented new and usefulImprovements in the Production of Mordant-Dyeing MonoazoColoring-Matter; and we do hereby declare that the following is a full,clear, and exact description thereof, which will enable others skilledin the art to which it appertains to make and use the same.

We have found that a valuable monoaz'o dyestuff is produced if the diazocompound derived from 4-chloro-2-amidophenol sulfonic acid is combinedwith the 1.8-amidonaphthol= 3.6-disulfonic acid. This dyestuff whenfixed on wool with the aid of copper salts yields shades which aredistinguished by their extraordinary clearness. Moreover, they areneither uneven nor dull, which inconveniences will often occur if dyeingwith coloring-matters susceptible of forming copper lakes is carried outin an acid-bath on the addition of copper salts.

For the production of the 4-chloro-2-amidophenol sulfonic acid employedas a parent material we proceed as follows: Twenty-five kilos of4-chloro-2-nitrophenol are heated with a solution of one hundred kilosof sodium bisulfite and five hundred liters of water in a vesselcombined with a reflux condenser and the mixture is kept boiling untilthe -chloro- 2-nitrophenol has disappeared, a clear solution thus beingformed. One hundred kilos of hydrochloric acid (specific gravity 12Baum) are now added thereto and the mass is boiled for some time inorder to expel the excess of sulfurous acid. On refrigeration the4-chloro-2-amidophenol sulfonic acid separates as a crystalline mass,easily soluble in boiling water, hardly soluble in cold water or inalcohol. Its sodium salt crystallizes from hot water in the form ofshining leaflets.

In order to transform the 4-chloro-2-amidophenol sulfonic acid into thenew monoazo dyestuff, we proceed as follows: 22.3 kilos of4-chloro-2-amidophenol sulfonic acid are diazotized in the Well-knownway by means of seven parts of sodium nitrite and mineral acid. Theyellowish diazo solution thus formed is run into a solution ofthirty-two kilos of 1.8-amidonaphthol-3.6-disulfonic acid, care beingtaken to keep the mixture alkaline by the addition of sodium carbonate.The new dyestuff is then precipitated from the solution obtained bymeans of common salt. It is filtered, pressed, and dried.

The result is not materially changed if for the above-described4-chloro-2-amidophenol sulfonic acid the isometric sulfo-acid issubstituted, which may be obtained by introduc ing one part, by weight,of 4-chloro-2-amidophenol into four parts of sulfuric acid monohydrate,heating the mixture gently for some time, and finally pouring it intoice-water.

The new dyestuff forms in the dry state a dark powder easily soluble inwater to a redviolet solution ,th-e coloration of which changes to blueon addition of sodium carbonate and to a fine red on the addition ofmineral acids. The dye dissolves easily in concentrated sulfuric acid,forming a red violet solution, which by dilution with ice-water turnsred. It is but hardly soluble in alcohol to a bluishred solution. Whenfixed on wool with the aid of copper salts, it yields fine blue shades,distinguished by their extraordinary fastness.

Having thus described our invention and in what manner the same is to beperformed, what we claim as new is- The new monoazo dye obtained bycombining diazotized 4-chloro-2-amidophenol sulfonic acid with1.S-amidonaphthol-B.6-disulfonic acids; said dye forming in the drystate a dark powder, easily soluble in water to a red-violet solution,the coloration of which changes to blue on the addition of sodiumcarbonate and to a fine red on the addition of mineral acids; the dyedissolving easily in concentrated sulfuric acid to a red-violetsolution, which by dilution with ice-water turns red; being hardlysoluble in alcohol to abluish-red solution; producing on wool, whenfixed with the aid of copper salts, fine blue shades of an extraordinaryfastness.

In Witness whereof we havehereunto signed our names, this 21st day ofJune, 1901, in the presence of two subscribing witnesses.

HUGO JAESSOHIN. OSKAR. KALTWASSER.

Witnesses 2 WOLDEMAR HAoPp, HENRY HASPER.

